dissimilar material contact with each other like- stainless steel contact with carbon steel

[Rameez khan RK]

Dear Experts,

            can any one tell me what is the cause if ss (stainless steel) in direct contact with cs (carbon steel). could anyone please define me as per standards and code.

Thank you 

RK  

[George Dilintas]

One tadvise : never write "ss". This is reminding Hitlers murderers . When CS comes in contact with Stainless Steel the protective layer of stable Cr Oxide is destroyed,  On the top of that the traces of CS do not allow the Cr to come into contact with O2 to create again the protective Cr Oxid layer and thus corrosion is initiated. This phenomenon is called "iron contamination".

I don't know if there is any Code or standard. However, this is basic metallurgy and corrosion knowledge.

Don't forget that there is no substitute to engineer's judgement.

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Dr. Georgios Dilintas,

Dipl. Ing. In Aeronautic and Space Engineering

Ph.D in Mechanics of Solids - Computational Mechanics

A.I.S, A.N.I, IRCA Lead Auditor

Welding, Stress Analysis, Corrosion, QA/QC, Failure Analysis, Risk Analysis

[atul khatri]

In addition to George's response , please don't overlook the " Galvanic Corrosion" if the below mentioned conditions exist in your case. 

           1. The metal joint must be wet with a conductive media (probable liquid media, or humid gas)

           2. There must be metal to metal contact

           3. Sufficient different potential between the metals in contact

All three conditions shall exist for galvanic corrosion.

 For more detail on potential differences between metal refer  "Astm G82 (Development and use of a galvanic series for predicting galvanic corrosion performance)"

Regards

Atul Khatri

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